The designing of an electronic device such as an integrated circuit chip is a complex, time consuming, and consequently costly procedure. The device design is frequently tested at various points during the design and implementation process to be certain that the device will perform as desired. In addition, during high volume manufacturing of the device, each unit of the device must be tested to be certain it is acceptable. The ultimate performance of the electronic device, however, is as a part of an overall system. In such use, the electronic device is generally mounted on a circuit board, such as a motherboard, and is electrically connected to other components on the circuit board. To test the device an input signal might be applied that simulates the input signal which the device is to receive during its regular operation on the circuit board, and the resulting output signal is monitored to see how it compares with the output signal that should be obtained during that regular operation. However, during the testing the input signal is provided by, and the output signal is applied to, test equipment, and not by and to other circuit components on the motherboard. That test equipment generally includes a general purpose tester and a tester interface unit that is designed for use with the specific electronic device under test. Even though the test equipment is designed to emulate the other circuit components on the motherboard, that emulation is not total. By way of example, signal propagation times are different. Output impedances, particularly, capacitances, may differ. In general, the integrity of the input and output signals is different during testing as compared with during actual use. As a result, performance on the test equipment does not accurately emulate the performance on the motherboard. This problem is exacerbated when there are multiple types of electronic devices, and so multiple types of inputs and outputs on the circuit board.